Internal combustion engine



Sept. 29, 1931. w. RIEHM INTERNAL COMBUSTION ENGINE Filed April 30, 1928 Patented Sept. 29, 1931 UNITED STATES PATENT OFFICE WILHELM RIEHM, OF AUGSBURG, GERMANY, ASSIGNOR TO THE FIRM MASCHINEN- FABRIK AUGSBURG-NUERNBERG AKTIENGESELLSCHAFT, OF'AUGSBURG, GERMANY,

A CORPORATION OF GERMANY INTERNAL COMBUSTION ENGINE Application filed April 30, 1928, Serial No. 273,951, and in Germany May 4, 1927.

This invention relates to internal-combustion engines, and more particularly to twostroke cycle engines.

One of the principal objects of the invention is to provide a two-stroke cycle engine,

having its fuel-inlet port aswell as its scavenging air-inlet port and its exhaust port piston controlled, which is efficient and satisfactory in operation, and a method in the operation of such an engine.

Another object of the invention is to provide an engine of this character which is arranged to be double acting.

Other objects and advantages of the invention will be apparent from the description thereof, set out below, and the accompanying drawings.

In the drawings, in which like characters of reference designate like parts throughout the several views thereof,

Fig. 1 is a longitudinal sectional view through the cylinder of a double-acting two stroke cycle engine constructed in accordance with-this invention;

Fig. 2 is a transverse sectional view along the line A-B of Fig. 1;

'Fig. 3 is a longitudinal sectional view through the cylinder of a double-acting twostroke cycle engine having a somewhat modified arrangement of ports;

Fig. 4 is a transverse sectional view along the line CD of Fig. 3;

Fig. 5 is a longitudinal sectional view through thecylinder of a double-acting two-' stroke cycle engine having still another arrangement of ports; and

Fig. 6 is a longitudinal sectional view through the cylinder of a double-acting twostroke cycle engine having another somewhat different arrangement of ports.

This invention is preferably employed in connection with a double-acting two-stroke cycle engine, adapted to operate upon an explosive mixture, and is so illustrated in the drawings. For purposes of easier description,- the drawings are somewhat diagrammatic in character, and only so much of the engine is illustrated as is needed for clear disclosure of the invention. As shown tlieaengine cylinder is designated by the letter a, and is of the double-acting type. Reciprocable within the cylinder is a piston 72, which during its reciprocation controls the fuel-inlet ports, the scavenging air-inlet ports, and the exhaust ports, and inasmuch as it is arranged to be double acting, two sets of each of these ports are provided, one set for each end of the cylinder. As shown in Fig. l the exhaust ports a for the upper end of the cylinder are arranged in the left half of the cylinder wall, and are connected, in suitable manner, to the exhaust manifold d. As shown these exhaust ports are arranged within a band extending substantially half way around the circumference of the cylinder wall; Located within the same half of the cylinder wall, and between the exhaust ports and a median transverse plane across the cylinder, are scavenging air-inlet ports 6, which are connected by suitable passages to the scavenging air manifold As shown in Fig. 1 the scavenging air-inlet ports e are arranged in a band extending circularly around a portion of the cylinder wall, but they occupy a band of less arcuate extent than the exhaust ports 0.

The opposite end of the cylinder, as shown in Fig. 1, is provided with similar exhaust ports 0 and scavenging air-inlet ports 6, which are respectively connected by similar passages to an exhaust manifold d and a scavenging air manifold f. These ports however are reversely positioned with respect to the corresponding ports in the upper half of the cylinder, so that they lie within the right half of the cylinder, as viewed in Fig. 1

Located within the cylinder wall, and in the space defined in its longitudinal dimensions by the two rows of exhaust ports, and its. circumferential dimensions by the opposite ends of the rows of scavenging airinlet ports, are two sets of gas or fuel inlet ports 9, each of which is suitably connected, by passages, to the gas-inlet manifold 71 It will be noted from reference to- Fig. 2 that these ports 9 are arranged so as to be symmetrical with respect to the median transverse plane of the cylinder and so as to be located, longitudinally, out of the arcuate bands within which the scavenging air-inlet ports are arranged. Furthermore these ports are positioned somewhat closer to the median transverse plane of the cylinder than are the scavenging air-inlet ports 6.

As will be evident from the drawing the several sets of ports 0, e and g' are controlled by means of the piston b, as it reciprocates from one end of the cylinder to the other, and the ports are soarranged that as the piston moves from either end to the center of the cylinder it first uncovers the exhaust ports, then the scavenging air-inlet ports, and then the gas-inlet ports; and on reverse movement closes those ports in the reverse order. Starting with the piston in the position shown in Fig. 1, for purposes of explanation, the piston as it moves toward the opposite end of the cylinder will first uncover the exhaust ports 0 for the upper end of the cylinder. This inner movement of course corresponds to a power stroke resulting from combustion of the fuel in the upper end of the cylinder. The exhaust gases resulting from such combustion, as the piston moves past and opens up the exhaust ports 0, will escape from the cylinder through such ports until atmospheric pressure is attained in this part of the cylinder. Upon further movement the piston will uncover the scavenging air ports e, and scavenging air will flow in, moving across the end of the piston and against the adjacent-o posite side of the cylinder, the wall of which is imperforate. The flowing scavenging air will then be deflected to ascend along the cylinder wall, will be again deflected and its path of travel reversed by the end of the cylinder and will descend along the opposite side of the cylinder wall,--that is the side in which are located the ports 0 and e for the upper part of the cylinder. This flowing air, moving toward the exhaust ports will force out of the cylinder any exhaust gas remaining therein. While this is occurring the continued movement of the piston will uncover the gas-inlet ports 9 so that fuel will be introduced into the cylinder concomitantly with the scavenging air, with the resultant formation of a combustible mixture. At this time all, or substantially all of the exhaust gas will have already been forced out of the cylinder, by the flowing scavenging air, through the ports a. If any exhaust as should still remain in the cylinder at t is time, nevertheless the combustible gas being directed into the cylinder below. the upper stratum of fresh scavenging air, a neutral clean stratum of scavengin alr will be interposed between the combusti le mixture and any such exhaust gas as may have remained, and therefore the mixture of air and gas will not be contaminated by such small fraction of exhaust gas as may perhaps remain within the cylinder. The rate at which exhaust as is driven out,

and the pressure wit in the cylinder, is determined by the area of the initial opening of the scavenging air ports, with resacct to the opening of the gas-inlet ports. ontinued motion of'the piston, which has now reached inner-dead center, will result in closing the several ports in the reverse order, the gasinlet ports being first closed, the scavenging air-inlet ports being then closed, and the exhaust ports thereafter closed. The further motion of the piston will result in compression of the combustible mixture, and at the proper time in the cycle the compressed mixture will be ignited, in any usual fashion, a conventional sparkplug being illustrated and designated by the letter m. During this up-stroke of the plston, which is the compression stroke in the upper end of the cylinder, the piston is.uncovering the exhaust ports 0, the scavenging air-inlet ports 0, and the gas-inlet ports 9 for the lower end of the cylinder, in the order named, in the manner already ;described with respect to the correspondlng, but oppositely positioned, ports in the wall of the upper end of the cylinder.

The functioning of the modified structures shown in Figs. 3, 4, 5 and 6 is the same as already described, with minor dlfferentlations hereinafter set out.

In Figs. 3 and 4 the relative placing of ports 0, e and g, with respect to the longitudinal travel of the'piston, is substantially the same. However, the gas-inlet ports 9 for the upper portion of the cylinder are located in the opposite portion of the cylinder Wall, substantially aligned. with the ports 0 and e for the lower part of the cylinder; while the gas-inlet ports for the lower part of the cylinder are located in the left portion of the cylinder wall, substantially in ali nment with the upper ports of the cylint er. As a result the fuel introduced through the ports 9 is directed through the ascending scavenging air streams. To more surely bring this about, each end of the piston is provided with a recess 2', which is positioned to receive the introduced fuel and to divert its flow so as to direct the gas upwardly,

of them being located at the left of Fig. 5.

By means of this arrangement both sets of scavenging air-inlet ports e may be connected to the same manifold f. In this con- :truction the gas-inlet ports 9 are located in the opposite part of the cylinder, and so may be served from a single manifold. In this arrangement a single set of gas-inlet ports serves for both halves of the cylinder, the ports being arranged to extend on both sides of the median plane of the cylinder.

In the form shown in Fig. 6 all of the ports are arranged in the same part of the cylinder wall, the exhaust ports extending over a greater arcuate distance than the scavenging air-inlet ports, the gas-inlet ports being located to lie opposite the ends of the scavenging air-inlet ports, and between the overlying exhaust ports. In this arrangement the gas manifold h may be conveniently arranged to lie inside of the scavenging air-inlet pipe f; Since the gas-inlet ports extend throughout a greater extent of the cylinder wall, they may be reduced in size, with advantageous results, and in addi-' tion a compact arrangement of the various conduits is secured.

\Vhile the forms of apparatus and the method herein described constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limited to the precise forms of apparatus or method,

and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is: v

l. A two-stroke cycle engine of the character described, with port scavenging; comprising a cylinder having an exhaust port, scavenging air-inlet port and fuel-inlet port in the wall thereof; and a piston reciprocable within said cylinder-to control said ports, said ports being so arranged that the: piston during travel in one direction will consecutively uncover the exhaust port, the scavenglng air-inlet port and the fuel-inlet port, the exhaust and scavenging air inlet ports being arranged on one side only of the cylinder providing for reverse scavenging flow from the air inlet port across, along, and back along the cylinder.

2. A two-stroke cycle engine of the character described, With port scavenging; comprising a cylinder having an exhaust port, a scavenging air-inlet port, and a fuel-inlet port in the wall thereof; and a piston reciprocable therein to control said ports, said ports being so arranged that during travel of the piston in one direction it will consecutively uncover the exhaust port, the scavenging-inlet port and the fuel-inlet port, and said scavenging air-inlet port and fuelinlet port being so relatively arranged as to be both open at the same time, to concomitantly introduce air and fuel into the cylinder, the exhaust, and scavenging air inlet ports being arranged on one side only of ing flow from the air inlet port across, along, and back along the cylinder.

3. A two-stroke c ole engine of the character described, witli port scavenging; comprising a cylinder having an'exhaust port, a scavenging air-inlet port and fuel-inlet port in the wall thereof, and a piston reciprocable therein to control said orts, said ports being so arranged that during travel of the iston in one direction it will consecutive y uncover the exhaust port, the scavenging air-inlet port and the fuel-inlet port,'and said scavenging air-inlet port and fuel-inlet: port being relatively so arranged that said scavenging air-inlet port will be opened only slightly in advance of the fuelinlet port, whereby the fuel is introduced into an atmosphere of air uncontaminated by exhaust gas remaining within the cylinder from previous combustion, the exhaust and scavenging air inlet ports being arranged on one side only of the cylinder providing for reverse scavenging flow fromthe air inlet port across, along, and back along the cylinder.

4. A two-stroke cycle engine of the character described, with port scavenging; comprising a cylinder having an exhaust port, a scavenging air-inlet ort and a fuel-inlet port in the wall thereo the exhaust port and the scavenging air-inlet port being arranged in general axial alignment within the cylinder wall with the exhaust port positioned between the scavenging air-inlet port and the end of the cylinder, and the portion of the cylinder wall opposite said ports being 1mperforate, and the fuel-inlet port being partly coextensive in positioning with the scavenging air-inlet .port but angularly spaced therefrom in the cylinder wall; and a piston reciprocable within said cylinder to c'ontrol said ports, the arrangement of said ports being such that during travel of the piston in one direction it will first uncover the exhaust port to permit the escape of exhaust gas from the combustion space of the cyl inder, will then uncover the scavenging airinlet port to permit the inflow of scavenging air across, along and back alongsaid combustion space to drive out remaining exhaust gas, and to then uncover the fuelinlet port, which is so arranged that fuel introduced therethrough will mix with the portion of scavenging air being concomitantly introduced so that a neutral stratum of such scavenging air will be maintained between the resulting fuel mixture and any residue of exhaust gas remaining in the cyl inder.

enging; comprising a cylinder having two '7 sets of scavenging .air inlet and exhaust ports arranged therein, one set at each end the cylinder providing for reverse scaveng-' part-circumferential bands of the cylinder wall to provide for reverse scavenging flow, the said bands being diametrically opposed and also located upon opposite sides of the median transverse plane of the cylinder, and also having two sets of fuel-inlet ports, longitudinally aligned and spaced to lie \upon opposite sides of the median transverse plane of the cylinder, and angularly spaced to lie between the opposed sets of scavenging air-inlet ports.

6. A double-acting two-stroke cycle engine of the character described, with port scavenging; comprising a cylinder having two sets of scavenging air inlet and exhaust ports arranged therein, one set at each end of the cylinder, said sets each lying within part-circumferential bands of the cylinder wall to provide for reverse scavenging flow, the said bands being diametrically opposed and also located upon opposite sides of the median transverse plane of the cylinder, and also having two sets of fuelinlet ports, longitudinally aligned and spaced to lie upon opposite sides of the median transverse plane of the cylinder, and

angularly spaced to lie between the opposed sets of scavenging air-inlet port s, each of said fuel-inlet ports comprising angularly spaced ports positioned to open through the wall of the cylinder at each side of the corresponding scavenging air-inlet'ports.

, 7. The method in the operation of twostroke cycle internal-combustion engines which comprises connecting the combustion space within the engine cylinder to atmosphere to permit escape of exhaust gas there-' from; thereafter flowing scavenging air across, along and back along said combustion space to drive out exhaust gas remaining within the combustion space; and thereafter during the continuance of introduction of scavenging air introducing fuel into said fiowin scavenging air to mix therewith, said uel and air being so introduced that a neutral. stratum of air is maintained between the resulting fuel mixture and any residue of exhaust gas remaining in the cyl- 4 inder.

8. A double-acting two-stroke cycle engine of the character described, with port scavengin comprising a cylinder having two sets 0 scavenging air-inlet and exhaust ports arran ed therein, .one set at each end of the cylin er, said sets each lying within partcircumferential bands of the cylinder wall,

the said bands being diametrically opposed and also located upon opposite sides of the median transverse plane of the cylinder, and

also "having fuel-inlet ports for the supply of fuel mixture to opposite sides of the {median transverse plane of the cylinder, and -'.a ngularly spaced to lie between the opposed sets of scavenging air-inlet ports.

9-; twogstroke cycle engine of the character described, with port scavenging, comprising a cylinder having exhaust, scavenging air inlet, and fuel inlet ports in the wall thereof, and a piston reciprocable within said cylinder to control said ports, said ports being arranged in substantial longitudinal alignment upon a single side of the cylinder wall so as to direct streams of scavenging air and fuel towards the opposite side of the cylinder wall and providing for reverse scavenging flow from the air inlet port, across, along, and back along the cylinder, and a piston reciprocable within said cylinder to consecutivel uncover the exhaust port, the scavenging air inlet port, and the fuel inlet port.

10. A two-stroke cycle engine of the character described, with port scavenging, comprising a cylinder having exhaust, scavenging air inlet, and fuel inlet ports in the wall thereof, and a piston reciprocable within said cylinder to control said ports, said ports being arranged in substantial longitudinal alignment upon a single side of the cylinder wall so as to direct streams of scavenging air and fuel towards the opposite side of the cylinder wall and providing for reverse scavenging flow from the air inlet port,

'across, along, and back along the cylinder,

the said bands being longitudinally aligned and located upon opposite sides of the median transverse plane of the cylinder, and

also having gas inlet ports, the said gas inlet ports being arranged in longitudinal alignment with the scavenging air inlet ports and between the said sets of scavenging air inlet ports.

12. A double-acting two-stroke cycle engine of the character described, with port scavenging, comprising a cylinder having two sets of scavenging air inlet and exhaust ports arranged therein, one set at each end of the cylinder, said'sets lying within-part circumferential bands of the cylinder wall, the said bands being longitudinally aligned and located upon opposite sides of the median transverse plane of the cylinder, and also having gas inlet ports, the said gas inlet ports being arranged in longitudinal alignment with and between the sets of scavenging air inlet ports, and exhaust, scavenging air, and fuel manifolds for the several sets of ports all arranged ona common side of the cylinder.

13 A two-stroke cycle engine ofthe character described, with port scavenging, com-. prising a cylinder having an exhaust port,

I scavenging air inlet port and fuel inlet port ports being arranged on one side only of the cylinder providing for reverse scavenging flow from the air inlet port across, along, and back along the cylinder, the fuel inlet port and the scavenging air inlet port being oppositelyarranged in the cylinder so that the fuel will be introduced into a stream of scavenging air. f

14. A two-stroke cycle engine of the character described, with port scavenging, comprising a cylinder having an exhaust port, scavenging air inlet port and fuel inlet port in the wall thereof, a piston reciprocable within said cylinder to-control sai'd ports, said ports being so arranged that the piston during travel in one direction will consecutively uncover the exhaust port, the scavenging air inlet port and the fuel inlet port, the exhaust and scavenging air inlet ports being arranged on one side only of the cylinder providing for reverse scavenging flow from the air inlet port across, along, and back along the cylinder, the fuel inlet port and the scavenging air inlet port being oppositely arranged in the cylinder so that the fuel will be introduced into a stream of scavenging air, and deflecting means on said piston for deflecting the stream of fuel entering the cylinder towards the end of the cylinder. v

15. A two-stroke cycleengine of the character described, with port scavenging, comscavenging, comprising a cylinder having two sets of scavenging air inlet and exhaust ports arranged therein, one set at each end of the cylinder, said setslying within part circumferential bands of the cylinder wall, the said bands being longitudinally aligned and located upon opposite sides of the median transverse place of the cylinder, and

also having a set of gas inlet ports common to both sets ofscavengingair inlet and exhaust ports, said common gas inlet ports being arranged in the cylinder wall diametrically opposite the scavenging air inlet ports.-

17 A double-acting two-stroke cycle engine of the character described, with port scavenging, comprising a cylinder having two sets of scavenging air inlet and exhaust ports arranged therein, one set at'each end of the cylinder,-said sets lying within part circumferential bands of the cylinder wall upon opposite sides of the median transverse plane of the cylinder, and also having gas inlet ports arranged in the cylinder wall diametrically opposite the scavenging air in let ports, and a piston for consecutively uncovering the exhaust ports, the scavenging air inlet ports and the fuel inlet ports, said piston having deflecting means for directing the incoming fuel towards the end of the cylinder.

In testimony whereof I have allixed my signature.

DR. \VILHELM RIEHM.

prising a cylinder having an exhaust port,

scavenging air inlet port and fuel inlet port in the wall thereof, a piston reciprocable within said cylinder to control said ports,

said ports being so arranged that the piston during travel in one direction will consecutively uncover the exhaust port, the scavenging air inlet port and the fuel inlet port, the exhaust and scavenging air inlet ports being arranged on one side only of the cylinder providing for reverse scavenging flow from the air inlet port across, along, and back along the cylinder, the fuel inlet port and the scavenging air inlet port being oppositely arranged in the cylinder so that the fuel will be introduced into a stream of scavenging air, and deflecting means on the side of the piston adjacent the fuel inlet port for deflecting the entering fuel and the flow of scavenging air towards the end of the'cylin er. 

